Transaction management in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a transaction in database management?

A transaction is a group of one or more operations performed as a single unit. It ensures that either all operations succeed together or none do, keeping data safe and consistent.

intermediate

What are the four key properties of a transaction (ACID)?

ACID stands for:<br>1. Atomicity - all or nothing<br>2. Consistency - data stays correct<br>3. Isolation - transactions don’t interfere<br>4. Durability - changes are saved permanently

beginner

How do you start a transaction in PHP using PDO?

Use the method beginTransaction() on your PDO object to start a transaction.<br>Example:<br>$pdo->beginTransaction();

beginner

What PHP PDO methods are used to save or cancel a transaction?

To save changes, use commit().<br>To cancel changes, use rollBack().<br>Example:<br>$pdo->commit(); or $pdo->rollBack();

beginner

Why is transaction management important in web applications?

It keeps data safe when multiple users or processes work at the same time. It prevents errors like partial updates or lost data, making apps reliable and trustworthy.

Which method starts a transaction in PHP PDO?

A initTransaction()

B start()

C openTransaction()

D beginTransaction()

The correct method to start a transaction in PHP PDO is beginTransaction().

What does the commit() method do in transaction management?

A Saves all changes made during the transaction

B Starts a new transaction

C Cancels the transaction

D Checks for errors

commit() saves all changes made during the transaction permanently.

Which ACID property ensures that transactions do not affect each other?

A Atomicity

B Durability

C Isolation

D Consistency

Isolation ensures that transactions run independently without interfering with each other.

If an error occurs during a transaction, which method should be called to undo changes?

A rollBack()

B commit()

C beginTransaction()

D save()

The rollBack() method undoes all changes made during the transaction.

Why is transaction management important in multi-user applications?

A To speed up the application

B To prevent data conflicts and keep data consistent

C To reduce server load

D To allow unlimited users

Transaction management prevents conflicts and keeps data consistent when many users access the system.

Explain the ACID properties of a transaction and why each is important.

Think about how each property helps keep data safe and reliable.

Describe how to use PHP PDO to manage a transaction including starting, committing, and rolling back.

Imagine you are making changes to a database and want to control when they are saved or undone.